2-(2-methylan ilino)-nicotinic acid

ABSTRACT

This invention relates to 2-(2-methylanilino)-nicotinic acid, the non-toxic pharmaceutically acceptable salts thereof and to the methods for the preparation and use thereof. The tangible embodiments of this invention are prepared by condensing a 2-halonicotinic acid, or a functionally reactive equivalent thereof, with an o-toluidine, or a functionally reactive equivalent thereof, to produce either 2-(2methylanilino)-nicotinic acid or a derivative which is convertible thereinto.

United States Patent Sherlock 1 Oct. 10, 1972 [5 Z-(Z-METHYLAN lLINO)-NlCOTlNIC [56] References Cited 72 ACID UNITED STATES PATENTS l t Margaret R. 1 shemck Blwmfidd 3,415,834 12/1968 Hoffmann eta]. ..260/295.5 R

[73] Assignee: Schering Corporation, Bloomfield, p m Rom Attorney-Raymond A. McDonald and Richard S. 22 Filed: March 26, 1911 Serbin 21 Appl. N6: 128,514 5mm.

Related Application This invention relates to 2-( Z-methylanilino )-nicotinic [63] Continuation-impart of Ser. No. 866,012, 0C1. acid, the non-toxic pharmaceutically acceptable salts I3, 1969, abandoned, which is a continuationthereof and to the methods for the preparation and in-part of Ser. No. 835.743, June 23, 1969, use thereof. abandoned" The tangible embodiments of this invention are [52] us CL 260/295 5 R, 424,266 prepared by condensing a Z-halonicotinic acid, or a [51 1m.Cl...2It:.1111: .:..C07d 31/36 fumimlly reactive equivalent hemfi with 58 Field of Search ..260/295.5 R wluidim, 3 funcfimlly reactive equivalent to produce either 2-( 2-methylanilino)-nicotinic acid or a derivative which is convertible thereinto.

3 Clalrm, No Drawings 2-(2-METHYLAN ILINO)-NICO'I'INIC ACID CROSS-REFER ENCE TO RELATED APPLICATION This application is a continuation-in-part of my copending application Ser. No. 866,012 filed Oct. [3, I969, now abandoned, which in turn is a continuationin-part of application Ser. No. 835,743 filed June 23, i969, now abandoned.

The invention sought to be patented in one of its composition of matter aspects is described as residing in the concept of having the molecular structure of 2- (Z-methylanilino)-nicotinic acid including the nontoxic pharmaceutically acceptable salts thereof.

The invention sought to be patented in another of its composition of matter aspects resides in the concept of pharmaceutical dosage forms containing a novel compound of this invention.

The invention sought to be patented in one of its process aspects is described as residing in the concept of producing analgesia upon the administration of a therapeutically effective quantity of the novel compounds of this invention.

In another of its process aspects, the invention sought to be patented resides in the concept of condensing a 2-halo nicotinic acid or a functionally reactive equivalent thereof with an o-toluidine or a functionally reactive equivalent thereof to produce either 2- (Z-methylanilino) nicotinic acid or a derivative which is convertible thereinto.

The compounds are preferably prepared by heating together a 2-halo (preferably chloro or bromo) nicotinic acid with an o-toluidine, said heating taking place in either a high boiling solvent such as xylene or cymene, or by merely melting the reactants in the presence of each other. In the melt procedure, the reaction temperature will rise as the reaction proceeds. The reaction is completed generally after l5 30 minutes and is evidenced by a fall in the reaction temperature. The fused melt is then treated with a dilute aqueous base, such as for example, sodium carbonate or sodium hydroxide, and is extracted with a water immiscible solvent. The product, in the form of the soluble salt, is in the aqueous layer and is precipitated therefrom by acidifying with a dilute mineral acid and it is then filtered.

Alternatively, a lower alkyl ester of the Z-halonicotinic acid may be employed as a reactant, said reactant being condensed with the toluidine moiety. The ester group is subsequently hydrolyzed. In some instances hydrolysis may occur during the reaction but the alcohol produced does not interfere with the desired reaction and is easily removed during isolation and purification.

In addition to the use of the reactants employed in the above-described reactions, other equivalently functioning reactants may be employed to produce the desired novel compositions of this invention. For example, instead of employing a 2-halonicotinic acid (or ester thereof), a nicotinic acid (or ester thereof) having an alkoxy, alkylthio, methylsulfonyl, nitro or other equivalently functioning substituent in the 2-position thereof may be so employed. In such instances, the same reaction conditions used in the previous reactions would be employed. Alternatively, an N-substituted otoluidine reactant may be heated with the foregoing 2- substituted nicotinic acids (or esters thereof) instead of employing the previously described o-toluidine. Such equivalently functioning N-substituted o-toluidine reactants include those o-toluidines wherein a hydrogen atom attached to the nitrogen atom has been replaced with substituents such as benzyl. lower alkyl or acyl. Again, in the use of these equivalently functioning reactants the previously described reaction conditions would be employed. In those instances wherein the N-substituted o toluidine reactant has been employed, the Z-(N-substituted-Z-methylanilino)-nicotinic acid (or ester thereof) may be subjected to standard procedures to remove the benzyl, lower alkyl and acyl radicals from the nitrogen atom. The preferred reaction may be summarized by the following schematic representation:

COOR 000R CH: 0 N N N'H'R" .H,

COOK

Hi wherein R is a member or the group consisting of hydrogen and lower alkyl', R is a member of the group consisting of alkoxy, alkylthio, methylsulfonyl and nitro; and R" is a member of the group consisting of lower alltyl, benzyl and acyl.

Alternatively, the compounds embraced within the concepts of this invention may also be prepared from 2- amino nicotinic acid (or ester thereof) by means of a nucleophilic displacement reaction with an o-tolylhalide. The preparation of these compounds by this route is affected in the same manner as in the previously described displacement reaction.

The foregoing reaction may be summarized by the following schematic representation:

A NH H; v N N 1 N V .1

lbydrolysis COOK EXAMPLE I 2-(Z-Methylanilino)-nicotinic acid by filtration. Concentrate the ether layer and triturate lo the residue with petroleum ether and filter. Recrystallize from petroleum ether yielding ethyl 2-(2- methylanilino)-nicotinate, m.p. 5 -60C. B. 2-(2Methylanilino)-nicotinic acid Reflux a solution of 32 g. methylanilino)-nicotinate in 250 ml. taining 124 ml. of 40 percent sodium hours. Remove the excess alcohol and neutralize with dilute hydrochloric acid. Filter and dry the neutralized product. Recrystallize from acetonitrile giving 2-(2- methylanilino)-nicotinic acid m.p. l67l68 C. as a yellow solid.

of ethyl2-(2- of ethanol conhydroxide for 8 EXAMPLE 2 2-( 2-Methylanilino)-nicotinic acid Heat a mixture of 9.4 g. of 2-chloronicotinic acid and l2.9 g. of o-toluidine to I60 C. in a metal bath. Covering the vessel, a vigorous reaction ensues with the temperature of the reaction mixture rising to 230 C. The reaction is completed in approximately l5 minutes and the completion is evidenced by a drop in the temperature of the reaction mixture. Extract and dilute the product of the reaction with dilute sodium hydroxide solution and benzene. Separate the aqueous basic layer and neutralize with dilute hydrochloric acid and filter to give 2-(2-methylanilino) nicotinic acid.

The tangible embodiments of this invention are acids, and are soluble in aqueous alkali. The alkali and the alkaline earth metal and amine salts of the novel compound may be prepared by methods well known in the art for the preparation ofa salt of a strong base with a weak acid. For example, the alkali metal salt, preferably the sodium salt, may be obtained by evaporation of an alkaline solution (cg, with sodium hydroxide) of the anilino-nicotinic acid described herein. Alternatively, non-aqueous media may be employed. For example, by mixing an alcoholic solution of the anilino-nicotinic acid together with an alcoholic solution containing a stoichiometric quantity of an al kali metal alkoxide and after evaporating the solvent, there is obtained the alkali metal salt which is soluble in water. In a similar fashion and by other known techniques other functional derivatives (i.e., other pharmaceutically acceptable salts) are prepared. Representative of such salts are, in addition to sodium, those wherein the cation is ammonium, diethanol am monium, potassium, lithium, calcium, aluminum and other such metals which advantageously allow for greater solubility or greater ease in formulation and are considered the full equivalent of the free carboxylic acid. Also included within this class of functional derivatives are the (hydroxamic) acid derivatives which are obtained by the condensation of an alkyl ester of the hereinabove described anilino-nicotinic acid with hydroxylamine hydrochloride in the presence of sodium methoxide.

The tangible embodiments of the invention, in the form of the free acid or non-toxic pharmaceutically acceptable salt thereof, possess the inherent applied use characteristic of exerting an analgesic effect as determined by standard laboratory test procedures. Thus, the compounds of this invention are useful in treating pain.

It is known that certain anilino nicotinic acids may produce analgesia but there is associated with then a concomitant anti-inflammatory activity. Indeed, the anilino-nicotinic acids under study today indicate that they are primarily useful as anti-inflammatory agents and only secondarily, if at all, are they considered as analgesics. Quite unexpectedly, it has been found that 2-(Z-methylanilino)-nicotinic acid and the non-toxic pharmaceutically acceptable salts thereof exhibit significant analgesic activity without concomitant anti inflammatory or ulcerogenic effects. Thus, these compositions of matter are extremely useful in those conditions wherein only analgesic therapy is indicated such as, for example, fractures, trauma, and toothaches as well as the usual conditions for which analgesic therapy is indicated.

In testing for analgesic activity an assay similar to that reported by Randall and Salitto [Randall, L0. and Salitto, JJ. A Method for the Measurement of Analgesic Activity on inflamed Tissue, Arch. Int. Pharmacology, Ther. [092409 (1957)] was employed wherein a group of five m'ale Charles River C-D rats (l20-l50 g.) were treated with the test drug one hour after one paw of each rat has been inflamed by a subplantar injection ofO.l ml. of 20 percent Brewer's yeast suspension in water. The comparison of the reaction time to withdraw the inflamed paw as compared to the time to withdraw a non-inflamed paw in response to a bullet-shaped piston applied at a linearly increasing rate (20 mm. of Hg./sec.) was measured in both paws at suitable intervals after drug administration. Based upon the abovedescribed assay, it was found that 2-(2- methylanilino)-nicotinic acid exhibited potent analgesic activity in a dosage range of about l0 mg. per kg. to about 40 per kg. of body weight per day.

In testing for in vivo anti-inflammatory activity, the acute Carrageenin Paw Test in rats was employed wherein groups of five male Charles River C-D rats (lZO-lSO g.) were orally administered 2-(2- methylanilino)-nicotinic acid one hour before the introduction of the carrageenin to the left hind paw of the rat. An initial paw volume was taken upon the administration of the carrageenin and a second volume reading taken 3 hours subsequent to said carrageenin administration.

Based upon the above-described assay for in vivo anti-inflammatory activity, it was found that 2'( 2- methylanilino)-nicotinic acid was devoid of significant anti-inflammatory activity at doses 9, l8 and 27 times the effective analgesic dose of said compound.

In their functions as therapeutically useful compounds, it is advantageous to administer the compounds to the host animal in admixture with an acceptable pharmaceutical carrier suitable for enteral of parenteral administration, said carrier constituting a major portion ofthe admixture. Such preparations may be in such forms as, for example, tablets, capsules and suppositories, or in liquid forms, as for example, elixirs,

emulsions, sprays and injectables. In the formulation of pharmaceutical preparations there can be employed such substances which do not react with the active substance, as for example, water, gelatin, lactose, starches, magnesium stearate, talc, vegetable oils, benzyl alcohols, gums, polyalkylene glycols, petroleum jelly and the like. The active ingredient of such pharmaceutical preparations is preferably present in the preparations in such proportions by weight that the proportion by weight of the active ingredient to be administered lies between 0.1 percent and 50 percent.

TABLET FORMULATION The following formulation provides for the manufacture of [000 tablets:

Grams (l) 2-(2-methylanilino )-nicotinic acid 25.0 (2) Lactose, U.S.P. l8l.0 (3) Corn Starch, U.S.P. 92.5

(4) Magnesium Stearate L5 Thoroughly granulate a mixture of 72.5 g. of corn starch and the lactose with a paste prepared by dissolving g. of corn starch in 100 ml. of hot distilled water. Dry the resulting granulation, add a blended mixture of the active ingredient (l) and the magnesium stearate. Thoroughly blend and then press into tablets of 300 mg. each.

CAPSULE FORMULATION The following formulation provides for the manufacture of 1000 capsules:

Grams (l 2( Z-methylanilino)-nicotinic acid 25.0

Lactose Magnesium Stearate PARENTERAL FORMULATION The following formulation provides for the manufacture of 1000 vials each containing 10 mg. of active ingredient, as the sodium salt.

Grams (l) Z-(Z-methylanilino)-nicotinic acid (sodium salt) l0.95 (2) Munobasic potassium phosphate 6.00 (3) Water for Injection U.S.P. q.s...a.d. 1.001.

Dissolve ingredients (1 (2) and (3) in approximately percent of the volume of water and filter the resulting solution. Add to the filtrate sufficient water to bring up to a 1,000 ml. volume. Sterile-filter the solution and aseptically fill l milliliter portions of the solution into 2 milliliter vials, then lyophilize. After the lyophilized cake is dry, aseptically stopper the vials with rubber plugs and sea].

I claim:

1. 2-(2-Methylanilino)-nicotinic acid and the nontoxic pharmaceutically acceptable salts thereof.

2. A compound of claim 1, said compound being 2- (Z-methyl-anilino -nicotinic acid.

3. A compoun of claim 1, sald compound being a non-toxic pharmaceutically acceptable salt of 2-(2- methylanilino)-nicotinic acid.

l l i I 

2. A compound of claim 1, said compound being 2-(2-methyl-anilino)-nicotinic acid.
 3. A compound of claim 1, said compound being a non-toxic pharmaceutically acceptable salt of 2-(2-methylanilino)-nicotinic acid. 